Skip to main content

Using X headers with Exchange

X-headers are user defined fields that can (and are) inserted into a mail header that can serve a number of roles and purposes. Some common ones that are used are x-mailer which descibes the name of the software used to send that email and x-scl which is used to store the IMF SCL value when a message is archived to the ucearchive directory by the IMF (note this is not used to pass the SCL between servers this is done though the xexch50 blob during message transfer).

If you want to make use of a x-header in a Exchange sink or CDO script its pretty easy. First off all you need to know is what the name of the x-header is. If your not sure i find the best way to find out is to look at a serial version of the email. For this you can save the message to a eml file using a script like this and then open the eml file in notepad.

set msgobj = createobject("CDO.Message")
msgobj.datasource.open mailurl
set stm = msgobj.getstream()
stm.savetofile "d:\myemail.eml"

Once you know what the X header field name is to retrieve or set a X header in a sink or script all you need to do is append the name of the x header to urn:schemas:mailheader: . For example one way of telling if a email is a delivery report of some sort is to see if X-DSNContext is set in the header of a message for example

set msgobj = createobject("CDO.Message")
msgobj.datasource.open mailurl
if msgobj.fields("urn:schemas:mailheader:X-DSNContext") <> "" then
Wscript.echo "Delivery Report"
else
Wscript.echo "Normal"
end if

If you want to create your own X-header in a SMTP event sink (say you wanted this to be processed by another sink somewhere else). It would look like this

Sub ISMTPOnArrival_OnArrival(ByVal Msg, EventStatus )

on error resume next
msg.fields("urn:schemas:mailheader:X-myfield") = "Email-Okay"
msg.fields.update
msg.datasource.save

End Sub

Popular posts from this blog

The MailboxConcurrency limit and using Batching in the Microsoft Graph API

If your getting an error such as Application is over its MailboxConcurrency limit while using the Microsoft Graph API this post may help you understand why. Background   The Mailbox  concurrency limit when your using the Graph API is 4 as per https://docs.microsoft.com/en-us/graph/throttling#outlook-service-limits . This is evaluated for each app ID and mailbox combination so this means you can have different apps running under the same credentials and the poor behavior of one won't cause the other to be throttled. If you compared that to EWS you could have up to 27 concurrent connections but they are shared across all apps on a first come first served basis. Batching Batching in the Graph API is a way of combining multiple requests into a single HTTP request. Batching in the Exchange Mail API's EWS and MAPI has been around for a long time and its common, for email Apps to process large numbers of smaller items for a variety of reasons.  Batching in the Graph is limited to a m
Read more

Sending a Message in Exchange Online via REST from an Arduino MKR1000

This is part 2 of my MKR1000 article, in this previous post  I looked at sending a Message via EWS using Basic Authentication.  In this Post I'll look at using the new Outlook REST API  which requires using OAuth authentication to get an Access Token. The prerequisites for this sketch are the same as in the other post with the addition of the ArduinoJson library  https://github.com/bblanchon/ArduinoJson  which is used to parse the Authentication Results to extract the Access Token. Also the SSL certificates for the login.windows.net  and outlook.office365.com need to be uploaded to the devices using the wifi101 Firmware updater. To use Token Authentication you need to register an Application in Azure https://msdn.microsoft.com/en-us/office/office365/howto/add-common-consent-manually  with the Mail.Send permission. The application should be a Native Client app that use the Out of Band Callback urn:ietf:wg:oauth:2.0:oob. You need to authorize it in you tenant (eg build a small ap
Read more

How to test SMTP using Opportunistic TLS with Powershell and grab the public certificate a SMTP server is using

Most email services these day employ Opportunistic TLS when trying to send Messages which means that wherever possible the Messages will be encrypted rather then the plain text legacy of SMTP.  This method was defined in RFC 3207 "SMTP Service Extension for Secure SMTP over Transport Layer Security" and  there's a quite a good explanation of Opportunistic TLS on Wikipedia  https://en.wikipedia.org/wiki/Opportunistic_TLS .  This is used for both Server to Server (eg MTA to MTA) and Client to server (Eg a Message client like Outlook which acts as a MSA) the later being generally Authenticated. Basically it allows you to have a normal plain text SMTP conversation that is then upgraded to TLS using the STARTTLS verb. Not all servers will support this verb so if its not supported then a message is just sent as Plain text. TLS relies on PKI certificates and the administrative issue s that come around certificate management like expired certificates which is why I wrote th
Read more
All sample scripts and source code is provided by for illustrative purposes only. All examples are untested in different environments and therefore, I cannot guarantee or imply reliability, serviceability, or function of these programs.

All code contained herein is provided to you "AS IS" without any warranties of any kind. The implied warranties of non-infringement, merchantability and fitness for a particular purpose are expressly disclaimed.